A method for producing helically wound incandescent elements has been disclosed in EP-A 149 282. Here, incandescent elements are helically wound continuously from an incandescent wire onto a core wire. The incandescent wire (coil) wound onto the core wire is subsequently heated to approximately 1900 to 2200.degree. C. to reduce stresses, for example by means of a laser, high frequency or resistance heating of the core wire. During this, the incandescent wire is clamped on the core wire. The aim is to minimize stresses in the coil. To extract the core wire from the wound incandescent wire, the coil is rotated relative to the core wire in the opposite direction. This complicated method is required because the inside diameter of the coil is matched to the outside diameter of the core wire, and therefore the adherence of the coil to the core wire cannot be avoided.
A similar method with thermal treatment of the incandescent wire to remove the stresses, and subsequent extraction of the core wire from the coil is disclosed in DE-A 34 35 323 and JP-A 49-67 481. The latter uses a lamp as the means for heating the coil to a temperature of between 600 and 900.degree. C.
Coils prepared in these ways do have good dimensional stability. However, the good dimensional stability has the very effect of preventing simple extraction of the core wire from the coil.